Standard cubic foot per minute

The MultiMode combustor (MMC) comes in two sizes. The MMC-5 unit consists of a 100-standard cubic foot per minute (scfm) thermal oxidizer and a 100-scfm catalytic oxidizer. The MMC-6 unit consists of a 150-scfm thermal oxidizer and a 200-scfm catalytic oxidizer. 

In 1994, the National Renewable Energy Laboratory [NREL, a national laboratory of the U.S. Department of Energy (DOE)] performed a cost comparison of PCO versus other air pollution control technologies. It was determined from this study that the cost per standard cubic foot per minute (scfm) increased with contaminant concentration but fluctuated little with fiow rate. For treatment of VOC concentrations above 1000 parts per million (ppm), the PCO systems became expensive relative to other technologies (D130905, p. 3). 

A major opportunity for savings is to reduce the flow of diluent or carrier gas (often air or nitrogen) at the source. For a gas stream containing both particulates and halogenated volatile organic compounds (VOCs), the minimum capital investment to abate this stream is about 75 per standard cubic foot per minute (scfm) of waste gas flow. 

Figure 33.13 shows an example of the estimated coohng airflow requirements necessary to hmit the stack air temperature rise to 175 °C as a function of cell voltage and FU at a current density of 0.7 A cm for a 5 kW SOFC system [8]. It can be seen that in this case, suitable operating points are those below the air blower upper hmit of 60 scfm (standard cubic foot per minute). 

Reporting is required for facilities that emit GHGs of 25,000 metric tons or more of C02e per year (approximately equal to 170,000 standard cubic foot per day of vented methane, 65 100-HP engines operating at full load, or one 900 standard cubic foot per minute flare). 

Since this type of conveyor is available in only one standard size, its capacity is determined by the belt speed and the fixed cross-sectional area. Tons-per-hour capacity is figured by multiplying the bulk density in pounds per cubic foot by the speed in feet per minute and a constant of 0.0021. Power requirements are quite low and figured in the same way as those for conventional belt conveyors. 

NFPA 88B—Standard for Repair Garages requires that areas below grade used for repair vehicles have a forced ventilation system capable of continuously removing at least 0.75 cubic feet of air per minute few each square foot (cfm/sq.ft.) of floor space [5.8]. This ventilation requirement helps prevent accumulation of heavier-than-air fuel vapors which could accumulate in below-grade areas. 

The capacity of certain standard sizes of bucket carriers handling material weighing 100 lb. per cubic foot and run at a speed of 50 ft. per minute is given in Table 13,... 

Where Xi is a constant depending upon the design and upon other conditions, T is the peripheral velocity or the tip speed of the wheel in feet per minute A is the gross area of the wheel in square feet w is the absolute density of the gas handled in pound per cubic feet 0.075 is the weight of standard air at 65°F. in pounds per cubic foot. 

The last factor presented here to rate filter media, is that of air permeability. This is the measurement of a filter medium s ability to pass air. Air permeability is stated in CFM, the number of cubic feet of air that could pass through a square foot of medium per minute at a given pressure rating to determine air flow. The standard equipment used for this rating in the USA is the Frazier differential pressure air permeability machine. The air permeability test is based on Frazier method number 5450, equivalent to Federal Test Method Standard number 191 and ASTM 0737-75(80). The test pressure is 0.01806 p.s.i. and the inches of water column is 0.5 in. 

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